Crystalline lens could be replaced by intraocular lens (IOL) in cataract surgery. Since IOL was first used in transplanting in 1949, various research effects have been carried out on IOL materials. As there is a great evolution on operation methods, with the advancement of operation methods, demands on the characteristics of IOL have also changed a lot. Recently, with the popularity of the phacoemulsification procedure, it is possible to open a very small incision to extract opaque crystalline lens and finish the operation. So demands on characteristics of implanted IOL have changed continuously. For example, characteristics of so-called foldable IOL make it possible to implant through the small incision in foldable form and open in the lens capsule. At the same time, various research effects have been carried out on IOL materials. Usually, polymethyl methacrylate (PMMA), silicone, acrylic and resin are widely used as the IOL materials, while polysiloxane and acrylic resin can be used as foldable IOL materials. Copolymers of ethoxyl methacrylate and methyl methacrylate may also have been used recently. On the other hand, during the studies on these kinds of material, in order to prevent from the effect of UV ray on the retina, they can contain an UV absorber such as hydoxylbenzophenone, hydroxylphenyl benzotriazole and so on. Moreover, in order to raise biocompatibility and prevent from deposition of cells, a polysaccharide such as heparin is coated on the IOL surface in practice.
There have been reports on the polymers whose partial structure unit is acrylic acid monomer with a characteristic pyrrolidone group in the present invention, especially those used in ocular lens, such as a copolymer of methacryloyloxyethyl-2-pyrrolidone and acrylic acid (JP Laid-Open 28705/1992), a polymer polymerized from the monomer which is formed from amidation of acrylic acid and pyrrolidone (JP Laid-Open 43208/1990), a polymer of polyoxyalkylene structure with a pyrrolidone group (JP Laid- Open 8218/1990) and so on. As for copolymers formed from three components, there have been reports only on a copolymer of vinyl pyrrolidone, ethoxyl methacrylate and methyl methacrylate (JP Laid-Open 105250/1978), a copolymer of the methacryloyloxy ethyl-2-pyrrolidone, alkyl methacrylate and fluoroalkyl methacrylate (JP Laid-Open 150197/1993). Moreover, the main object of these studies is the application on soft contact lens and not on IOL. There have been no report especially on the possibility of application of foldable IOL in the invention.